Impressive, but you're telling us what many T1s have already discovered (and what many dieticians disagree with). The last time I had to meet with a dietician (in order to get a new authorization for my pump....absurd given my experience with T1), I got into a heated debate with her about exactly how many carbs I should be eating. Her "professional" opinion was that, given my intensive level of activity, I should be eating upwards of 250g carbs/day. Yes, that was seriously her recommendation! I laughed. If I ate that many carbs per day, my BG would be all over the freaking place and I'd be taking a ton of insulin to cover not only the meals, but also the post-meal spikes. I would constantly be going high and low and would likely gain a few pounds from all the yo-yoing.
It sounds like what you're experiencing is the benefits of limiting the carbs. Your basal rate dropped because not only did you lose weight, but you probably also eliminated any insulin resistance you were experiencing in the process. The exercise also helps diminish insulin resistance.
Years and years ago, many of us T1s followed restrictive, low-carbohydrate diets (exchange style), in large part because the insulins were not as good/effective. Meals and snacks had to be eaten with great regularity, regardless if you were hungry or not. When things switched over to carb counting (in the 90s?), there was this sudden switch in telling T1s that they could eat whatever they wanted!
Here's what I have discovered - my pancreas is broke so, no, I can't really just eat whatever I want and still feel good. The pump and carb counting DOES enable me more flexibility in what I eat, and I LOVE that. I don't have to eat around my insulin like we did in the old days and I can even have small treats on the rare occasion that I'm really craving it. BUT, can I eat like a "normal" American? No. I can't eat pizza or loads of carbs or sweets on a regular basis. Doing this would send my BGs into a tizzy. Quite frankly, I like the discipline that I've developed over the years. I don't think anyone, diabetic or not, needs to be eating a ton of carbs. It's just not healthy for anyone IMO.